Widening of the popliteal hiatus on sagittal MRI view plays a critical role in the mechanical signs of discoid lateral meniscus.

PURPOSE: This study was undertaken to elucidate the clinical significance of widening of the popliteal hiatus on magnetic resonance imaging (MRI) after a torn discoid lateral meniscus (DLM). METHODS: Included are 125 knees with meniscal disorders after arthroscopic surgery, divided according to preoperative MRI and symptoms into group A (torn DLM with mechanical symptoms,11 knees); group B (torn DLM without mechanical symptoms,41 knees); group C (asymptomatic DLM, 19 knees); and group D (medial meniscal tears, 54 knees). Popliteal hiatus width was measured on sagittal and coronal MRI. During arthroscopy, total meniscectomy or central partial meniscectomy combined repair of the remaining part was performed in group A and group B. Outcomes were evaluated with MRI, the Tegner, Lysholm Knee Scoring Scale, and visual analog scale (VAS) scores. RESULTS: The preoperative width of the popliteal hiatus was significantly larger in group A than in groups C and D (P < 0.05) on both views. Group A had a wider popliteal hiatus on sagittal view compared with group B (P < 0.05); group B had a wider popliteal hiatus on coronal view compared with group D (P < 0.05). The width of the popliteal hiatus on sagittal view was significantly reduced after surgery in group A (P < 0.05). In groups A and B, Lysholm and Tegner scores were improved, while VAS scores were reduced (all P < 0.05). CONCLUSION: Widening of the popliteal hiatus on MRI was correlated with torn DLM and accompanied mechanical symptoms. Arthroscopic central partial menisectomy and stabilization of the posterior part of the middle body anterior to the popliteus tendon were effective for the treatment of torn DLM. These findings may help guide appropriate treatment for torn DLM. LEVEL OF EVIDENCE: II.

Widening of the popliteal hiatus on magnetic resonance imaging leads to recurrent subluxation of the lateral meniscus.

PURPOSE: This study was undertaken to elucidate the clinical significance of widening of the popliteal hiatus on magnetic resonance imaging (MRI), and to document the clinical results and technical aspects of arthroscopic repair of this finding. METHODS: Included are 82 knees after arthroscopic surgery, divided according to arthroscopic diagnosis into group A, hypermobility of lateral meniscus, 8 knees; group B, tear of the anterior horn of the lateral meniscus, 32 knees; and group C, no abnormality of the lateral meniscus, 36 knees with medial meniscal tears and 6 with other conditions. Popliteal hiatus diameter was measured and the popliteal hiatus/lateral tibial plateau (LTP) ratio was calculated on preoperative sagittal and coronal MRI. At arthroscopy, the widened popliteal hiatus in group A was tightened anteriorly by outside-in or all-inside suture and posteriorly with all-inside suture. Outcomes were evaluated with MRI, Lysholm, Tegner and VAS scores. RESULTS: The preoperative diameter of the popliteal hiatus and the popliteal hiatus/LTP ratio were significantly larger in group A than in groups B and C (p < 0.05) on both views. Threshold popliteal hiatus/LTP values of 0.16 and 0.18 on the sagittal and coronal views demonstrated diagnostic discrimination, and these values were significantly reduced after arthroscopy in Group A. Lysholm and Tegner scores were improved after tightening of the popliteal hiatus, while VAS scores reduced (all p < 0.05). CONCLUSION: Widening of the popliteal hiatus on MRI may lead to recurrent subluxation of the lateral meniscus. Arthroscopic anterior and posterior tightening of the popliteal hiatus was a safe and effective treatment. LEVEL OF EVIDENCE: II.

Articular Cartilage Fragmentation Improves Chondrocyte Migration by Upregulating Membrane Type 1 Matrix Metalloprotease.

OBJECTIVE: This study was undertaken to elucidate the mechanism of improved chondrocyte migration after juvenile articular cartilage fragmentation. DESIGN: In vitro organ culture with rabbit cartilage fragments and cell culture with rabbit chondrocytes were performed. In part A, minced juvenile cartilage fragments (~0.5 × 0.5 × 0.5 mm) from rabbits, planted in gelatin sponge and fibrin glue, were cultured for 2, 4, or 6 weeks in vitro and compared with the cartilage chunks (~4 × 4 × 1 mm) and membrane type 1 matrix metalloprotease (MT1-MMP) inhibitor groups. Chondrocyte outgrowth was evaluated on histology and confocal laser scanning microscopy. MT1-MMP expression was compared between the cartilage fragment group and the cartilage chunks group. In part B, articular chondrocytes were harvested from juvenile rabbits, MT1-MMP was transfected into the cells, and cell migration was evaluated using the Transwell and wound healing tests. RESULTS: The histology and confocal microscopy results revealed that cell accumulation occurred at the edge of cartilage fragments, and outgrowth was better in the cartilage fragment group than those in the cartilage chunks group. Similar results were observed for MT1-MMP expression. After MT1-MMP inhibition, cells did not accumulate at the edge of the cartilage fragments, and chondrocyte outgrowth did not occur. Furthermore, overexpression of MT1-MMP enhanced the migration of articular chondrocytes. CONCLUSIONS: Juvenile articular cartilage fragmentation improved chondrocyte migration by upregulating MT1-MMP.

[Combined operation involving tibial tubercle distalization for recurrent patellar dislocation with patella alta].

Objective: To explore the clinical effects of combined operation involving tibial tubercle distalization for the recurrent patellar dislocation with patella alta. Methods: Between April 2010 and May 2016, 14 cases of recurrent patellar dislocation with patella alta were treated with combined operation involving tibial tubercle distalization. There were 5 males and 9 females with an average age of 18.5 years (range, 13-26 years). The left knee was involved in 9 cases and the right knee in 5 cases. The patella had dislocated 3.3 times on average (range, 2-5 times). The interval between the first dislocation and admission was 19.7 months on average (range, 4-60 months), and the main symptoms were knee pain and limited knee movement. Preoperative X-ray films, CT, and MRI examinations of knee joint showed that the epiphyseal plate closed in all patients. Of all patients, 3 patients had avulsion fracture of the inner edge of patella, and 2 patients had free body in articular cavity. The tibial tuberosity-trochlear groove (TT-TG) distance, patellar-trochlear-groove distance, Caton-Deschamps index, knee range of motion (ROM), Lysholm score, International Knee Documentation Committee (IKDC) score, Kujala score, and Tegner score were compared pre- and post-operation. Results: All patients had primary wound healing. All patients were followed up 24-72 months with an average of 34.6 months. X-ray film and CT examination showed that the patellar dislocation was corrected and the osteotomy of the tibial tubercle healed with an average healing time of 3.8 months (range, 3-5 month). At 1 day and 1 year after operation, the TT-TG distance, patellar-trochlear-groove distance, and Caton-Deschamps index showed significant differences when compared with preoperative values ( P<0.05), but there was no significant difference between 1 day and 1 year after operation ( P>0.05). At the 1 year and 2 years after operation, the knee ROM, Lysholm score, IKDC score, Kujala score, and Tegner score showed significant differences when compared with preoperative values ( P<0.05), and there was no significant difference between the 1 year and 2 years after operation ( P>0.05). Conclusion: Combined operation involving tibial tubercle distalization is a safe and reliable method, which has satisfactory short-term effectiveness for the recurrent patellar dislocation with patella alta.

[Research progress in diagnosis and treatment of injury of the popliteal meniscal fiber bundle].

Popliteal meniscal fiber bundle injury is relatively infrequent in clinic, which can be either isolated or associated with anterior cruciate ligament rupture, lateral meniscus injury and so on. Popliteal meniscal fiber bundle injury often leads to instability of lateral meniscus. Because of the lack of specific symptoms and signs of injury, the imaging changes are subtle, and it is easy to miss diagnosis and misdiagnosis in clinical. Timely diagnosis and treatment are essential to prevent the chronic pain and instability of the knee joint. This paper summarizes the anatomical characteristics, biomechanics, injury mechanism, diagnostic points and surgical treatment of the popliteal meniscus fiber bundle injury, in order to guide the diagnosis and treatment of the injury of the popliteal meniscus fiber bundle in the clinical work.